Third generation partnership project (3GPP) dealing with LTE is the latest standard in the mobile network technology. An object of LTE is to offer increased capacity and data rates for the users for mobile broadband. LTE meets the requirements of downlink data rates of at least 100 Mbit/s and uplink data rates of 50 Mbit/s. LTE also meets the requirement of a maximum round trip time of 30 MS.
Contrary to former mobile communication systems, LTE supports Frequency Division Duplex (FDD) and Time Division Duplex, (TDD). As a consequence, radio resources for LTE can be represented by a two dimensional grid, see FIG. 1, illustrating normal Cyclic Prefix (CP) condition. In the grid of FIG. 1, a Resource Element 100 (RE) comprises one subcarrier as indicated on the frequency axis and a minimum time unit as indicated on the time axis. During the minimum time unit, twelve subcarriers constitute one Orthogonal Frequency Division Multiplexing (OFDM) symbol. For normal CP seven consecutive OFDM symbols, i.e. 0.5 ms, constitute a Resource Block forming one time slot. For extended CP, six consecutive OFDM symbols, i.e. 0-0.5 ms, constitute a Resource Block, forming one time slot. The minimum scheduling unit consists of two resource Blocks (RBs) within one subframe of 1 ms, i.e. 14 consecutive OFDM symbols for normal CP, and 12 consecutive OFDM symbols for extended CP.
An RE has a specific energy, normally referred to as Energy Per Resource Element (EPRE) also usually denoted EA and EB. Some of the REs comprise reference signals, which also have an EPRE, denoted ERS.
Downlink power allocation is disclosed in Technical Specification (TS) 3GPP TS 36.213 entitled: “Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures” in which disclosed two parameters, which define a ratio
      ρ    A        ρ    B  among different types of REs to satisfy system requirements, wherein ρA is the ratio of the Physical Downlink Shared Channel (PDSCH) EPRE which OFDM symbol comprises no cell-specific RS to cell-specific RS and ρB is the ratio of PDSCH EPRE which OFDM symbol comprises cell-specific RS to cell-specific RS.
ρA can be expressed as
      ρ    A    =            E      A              E      RS      and ρB can be expressed as
            ρ      B        =                  E        B                    E        RS              ,where EA is PDSCH EPRE for OFDM symbols comprising no cell-specific RS, EB is PDSCH EPRE for OFDM symbols comprising cell-specific RS and ERS is the energy of cell-specific RS.
Further, according to 3GPP TS 36.213, ρA is also equal to δpower offset+ρA+1olog1o(2) when the user Equipment (UE) receives a PDSCH data transmission using pre-coding for transmit diversity with 4 cell-specific antenna ports; or equal to δPower offset+PA otherwise; where δpower offset is 0 for all PDSCH transmission schemes except multi-user MIMO and where PA is a UE specific parameter provided by higher layers and specified in 3GPP TS 36.331 entitled: “Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification”. 
In order to determine EPRE, it is common to configure PA and PB provided by higher layers and select a ratio for
            ρ      A              ρ      B        .
According to 3GPP TS 36.331, PB is a common parameter, which is used to configure cells, whereas PA is a UE specific parameter, which is used to configure UE parameters. PB is an integer and selected from the domain [0, 3], while PA is selected from a special domain comprising eight values.
The value of PA influences the power of the REs, hence it is important to obtain the best value of PA to guarantee the efficiency of power usage and power limit.
For a certain OFDM symbol, the power of the REs for a UE is determined as disclosed above. However, the frequency resource allocated to a UE comprises several subcarriers since an RB comprises 12 subcarriers. The same power is allocated to the different subcarriers. This has some drawbacks. In certain circumstances, the channel qualities may vary quickly, e.g. if the UE is moving about in the cell. In such circumstances, the power allocation may not be able to follow the rapid changes in channel qualities. This will cause a waste of power and low efficiency with regards to power usage. Furthermore, it will decrease system performance.
Still further, in the power allocation, no consideration is usually taken to fairness. Fairness is dealt with in radio resource scheduling. A scheduling function which does not consider fairness, typically only considers channel quality or condition when scheduling radio resources. Such a scheduling function will allocate radio resources primarily to UEs having favorable channel quality or condition and as a result will starve other UEs having unfavorable channel quality or condition. When scheduling radio resources, the scheduling function may make use of a fairness factor in order to schedule radio resources based both on channel quality and to avoid starving UEs having unfavorable channel quality or condition. One example of a scheduler employing fairness in scheduling radio resources to UEs in the cell is disclosed in the Francesco D Calabrese et al: “Performance of Proportional Fair Frequency and Time Domain Scheduling in LTE Uplink”, European Wireless 2009.